Bartter syndrome type 3 in an elderly complicated with adrenocorticotropin-deficiency

Bartter syndrome (BS) is a disorder with normotensive hypokalemic alkalosis and hyperreninemic hyperaldosteronemia. BS affects infants or early childhood. Patients with BS type 3 harbor mutation in CLCNKB, Cl channel Kb. Gitelman syndrome (GS) is a disorder in childhood, with mutation in SLC12A3. Isolated adrenocorticotropin deficiency (IAD) causes secondary adrenal insufficiency. Neither elderly cases, nor cases with IAD were previously reported in BS. A 72-year-old man was admitted with acute adrenal crisis. He had been treated for IAD for 19 years. He had no trouble during perinatal period, delivery, and growth. After the recovery from adrenal crisis, laboratory tests revealed hypokalemia; 3.0 mEq/L (normal: 3.5-4.5), impaired renal function: eGFR; 37.6 mL/min/1.73 m2, normomagnesemia; 2.1 mg/dL (1.7-2.3), hyperreninemia; 59.4 ng/mL/h (0.2-2.7), hyperaldosteronemia; 23.5 ng/dL (3.0-15.9), and normal urinary ratio of calcium/creatinine. In diuretic tests, he showed a fine response to furosemide, and a mild response to thiazide. In genetic tests, no mutation of SLC12A3 was found and homozygous mutation: c.1830 G > A in CLCNKB was shown. Thus he was diagnosed as BS type 3. Current case presented with unusual features as BS type 3, 1) his late and mild clinical manifestation suggested GS rather than BS, 2) laboratory data and diuretics tests did not show typical features as BS, and 3) IAD and chronic renal failure altered electrolyte metabolism. In conclusion, current case implies that BS type 3 should be considered even in elderly cases with normotensive hypokalemia, and highlights importance of endocrinological and genetic examinations.